Emergency maintenance plan for lithium battery packs

First, emergency response to fire

Identify the characteristics of the fire

When a lithium battery pack emits smoke, has an odd smell (similar to the pungent odor of burnt plastic or the evaporation of electrolyte), and then the flame spreads rapidly, which may be bright orange-yellow in color and accompanied by crackling sounds, it can be determined that it is on fire. The causes of fire may include overcharging, internal short circuit, external short circuit, mechanical damage, etc. For instance, prolonged use of a mismatched charger to charge a lithium battery pack can cause lithium dendrites inside the battery to grow and Pierce the separator, leading to a short circuit and fire.

Processing steps

Personnel evacuation: Immediately evacuate the personnel on the scene to ensure their safety. A fire in a lithium battery pack may be accompanied by dangers such as explosion and the release of toxic gases. People should stay at least 50 meters away from the fire source and be in the upwind direction.

Cut off the power supply: Quickly disconnect the power of the lithium battery pack, turn off the power switches of related devices, and unplug the connection wires between the battery pack and external devices. This is to prevent the fire from spreading due to continuous power supply and at the same time avoid the risk of electric shock.

Use of fire extinguishing equipment: Prioritize the use of carbon dioxide fire extinguishers or dry powder fire extinguishers for fire suppression. Carbon dioxide fire extinguishers put out fires by isolating oxygen and will not cause further damage to the battery pack. Dry powder fire extinguishers can suppress the combustion reaction. When in use, stand upwind, 2 to 3 meters away from the fire source, and aim at the base of the flame to spray. If there are no professional fire-fighting equipment on the spot, a large amount of dry sand can also be used to cover and extinguish the fire. Dry sand can isolate the air, lower the temperature and achieve the purpose of extinguishing the fire.

Continuous monitoring: After the fire is extinguished, the condition of the lithium battery pack should be continuously monitored to prevent re-ignition. Because the chemical reactions inside the lithium battery pack may not stop immediately, there is still a possibility of another fire. The monitoring time should be no less than 2 hours. During this period, it is necessary to closely observe whether there are any phenomena such as smoke, odor or temperature rise in the battery pack.

Second, emergency response to leakage

Identify leakage characteristics

When a lithium battery pack leaks, you may see the electrolyte flowing out. The electrolyte is usually colorless or light yellow liquid and has a corrosive and pungent smell. The possible causes of leakage could be damaged battery casing, aging and failure of seals, etc. For instance, if the battery pack is hit by an external force, causing the casing to crack, the electrolyte will leak out.

Processing steps

Personnel protection: Personnel handling leaks must wear protective equipment, including acid and alkali resistant gloves, goggles, gas masks, etc. The electrolyte is corrosive and can burn the skin and eyes. Meanwhile, the gas it volatilizes may cause harm to the human respiratory system.

Isolate the leakage area: Set up warning lines and prohibit irrelevant personnel from entering the leakage area. Prevent others from coming into contact with the leaked electrolyte to avoid causing personal injury.

Collect the leaked substance: Use inert materials such as liquid-absorbing cotton and sand to absorb the leaked electrolyte. Cover the leaked electrolyte with absorbent cotton or sand. After it is fully absorbed, carefully collect it and place it in a dedicated sealed container.

Clean up the site: Rinse the leakage area with a large amount of clean water to dilute and wash away the remaining electrolyte. The wastewater after rinsing should be treated as hazardous waste and must not be discharged at will.

Inspect the battery pack: Conduct a comprehensive inspection of the leaked lithium battery pack to determine the cause of the leakage. If the shell is damaged, it needs to be repaired or replaced. If the seal is aged, a new one should be replaced. After repair or replacement, a sealing test should be conducted to ensure that the battery pack no longer leaks.

Third, emergency handling for short circuits

Identify short-circuit characteristics

When a lithium battery pack short-circuits, the temperature of the battery pack will rise sharply, which may be accompanied by phenomena such as smoke and sparks. The causes of a short circuit may be direct contact between the positive and negative terminals of the battery, or damage to the connecting wire causing the positive and negative terminals to overlap, etc. For instance, if the insulation layer of the connecting wires in a battery pack is damaged and the exposed parts of the positive and negative electrodes come into contact with each other, a short circuit will be triggered.

Processing steps

Cut off the power supply: Immediately cut off the power supply of the lithium battery pack to prevent short-circuit current from further damaging the battery pack and to avoid more serious accidents such as fires.

Isolated battery pack: Isolate the short-circuited lithium battery pack from other devices or items to prevent the heat and sparks generated by the short circuit from igniting the surrounding flammable materials.

Check the short-circuit area: Under the condition of ensuring safety, inspect the short-circuit area of the battery pack. If the connecting wire is short-circuited, a new connecting wire needs to be replaced and it should be ensured that the insulation performance of the connecting wire is good. If it is an internal short circuit of the battery, the battery needs to be removed from the battery pack for further inspection and treatment.

Pre-use inspection: After the short-circuit issue is resolved, conduct a comprehensive performance inspection of the battery pack, including the detection of parameters such as voltage, internal resistance, and capacity. The battery pack can be put back into use only after its performance has returned to normal.

Fourth, emergency response to overcharging

Identify overcharge characteristics

When the charging time of a lithium battery pack exceeds the normal charging time and the temperature of the battery pack rises significantly with its surface getting hot, overcharging may have occurred. Overcharging can lead to an increase in the internal pressure of the battery, the decomposition of the electrolyte, and the generation of gas, causing the battery to bulge.

Processing steps

Stop charging: Immediately stop charging the lithium battery pack and unplug the charger. Prevent the battery from continuing to overcharge to avoid causing more serious safety accidents.

Cool the battery pack: Place the overcharged lithium battery pack in a well-ventilated area and let it cool naturally. Do not use a fan to blow directly on the battery pack to avoid generating static electricity and causing danger. The cooling time should be determined based on the temperature of the battery pack and generally needs to be cooled to room temperature.

Inspect the battery pack: After the battery pack has cooled down, check its appearance for any bulges, deformations or other conditions. Meanwhile, professional battery testing equipment is used to test the voltage, internal resistance and other parameters of the battery pack to determine whether the battery pack is damaged.

Subsequent processing: If the appearance of the battery pack shows no obvious damage and the detection parameters are within the normal range, a shallow charge and shallow discharge cycle can be performed to observe whether the performance of the battery pack has returned to normal. If the battery pack bulges, deforms or has abnormal detection parameters, its use should be stopped and it should be treated as hazardous waste.